Blasteroids is one of the sequels to the original 1979 shoot 'em up video game Asteroids. It was developed by Atari Games (which later became Midway Games West) and released as a coin-operated game in 1987, and in 1989 by Image Works for Amiga, Amstrad CPC, Atari ST, C64/128, MSX, MS-DOS PC, and ZX Spectrum.
The gameplay for the game is basically the same as for the original; the player (or players in case of a 2-player game) controls a spaceship viewed from "above" in a 2D representation of space, by rotating the ship, and using thrust to give the ship momentum. To slow down or completely stop moving, the player has to rotate the ship to face the direction it came from, and generate the right amount of thrust to nullify its momentum. The ship has a limited amount of fuel to generate thrust with. This fuel comes in the form of "Energy" that is also used for the ship's Shields which protect it against collisions and enemy fire. Once all Energy is gone, the player's ship is destroyed. The ship can shoot to destroy asteroids and enemy ships. The ship can also be transformed at will into 3 different versions, namely the "Speeder", the fastest version, the "Fighter", which has the most firepower, and the "Warrior", which has extra armour.
At the start of the game, the player is in a screen with 4 "Warps" indicating the game's difficulty: Easy, Medium, Hard, and Expert. Flying through any of the Warps starts the game with that difficulty. Each Warp has several "Galaxies", each with 9 or 16 "Sectors" (levels), depending on difficulty. Once a Sector is completed by destroying all the asteroids, an "Exit Portal" (another Warp) appears to lead the player to the "Galactic Map" screen. Similarly to the difficulty screen, the player can here choose which Sector to visit next. Completed and empty Sectors can be revisited, but this costs Energy. Sectors that are currently out of range are marked with a "?".
Each level (called "Sector" in the game) consists of only the visible screen. The top and bottom of the screen are connected, as are the left and right side of the screen, meaning if anything leaves the screen, it will appear again on the opposite side. (A Sector can be thought of as the surface of a torus laid out flat.)
The object of the game is to destroy all the asteroids which have a set speed at which they fly through the Sector. Asteroids come in varying sizes, and when shot, larger asteroids break into multiple smaller ones. Only shooting the smallest ones will actually remove them from the Sector. Asteroids also come in different types. Normal asteroids don't contain anything, but red asteroids can contain power-ups in the form of Power Crystals that are released by completely destroying asteroids. Crystals decay over time. Popcorn Asteroids require several hits, which expands their size, and eventually makes them stop spinning. They can't be destroyed, but stopping them is enough to finish each Sector. Egg asteroids contain leeches which home in on the user's ship and suck out its energy. They can be shot and destroyed. Finally there are Seeker asteroids which home in on the player's ship after being shot.
A second player can join the game at any time by pressing his Fire button, using up 1 credit and turning Blasteroids into a multiplayer game. Both players can cooperate by covering each other, as well as by docking their ships. Docking is possible if one ship is a Speeder, and the other is a Warrior; flying over each other will turn the Speeder into a stationary turret with more firepower on top of the Warrior, which turns into a Starlet, with less firepower but full control. The ships undock when either player transforms their ship into something else again. The first player to exit through the Exit Portal gets a large bonus and control of the Galactic Map.